Radio beacon and radio guide



Y. ROCARD 2,206,644

RADIO BEACON AND RADIO GUIDE Filed April 30, 1938 1 M G. J. v

/0 /0 fia4a/ j? /6 556 3nnenfor Yves Rocard 702 I attorney Patented July 2, 1940 l STATS RADIO BEACON AND RADIO GUIDE corporation of France Application April 30, 1938, Serial No. 205,247 In France May 21, 1937 '1 Claims.

The present invention aims at providing a vehicle (aircraft, ship, etc.) receiving a radio guide signal, with indications of the position relative to the axis marked by the radio guide and which are more precise than those furnished by the systems known as such.

It is known that among radio guides with interlocking signals there exist two principal types, the one which marks from a point two directions, thus providing one kind of signals (dots for instance) in an entire sector in space, and another kind of signals (dashes for instance) appearing in the entire complementary sector, the other principal type of guide, however, marks four directions and divides the space into four sectors whereby two that are diametrically opposite are characterized by dots and the other two by dashes.

It can be seen directly that the beacon of the first type furnishes a signaling without ambiguity but an incomplete signaling whereby the pilot knows whether he is on the one side or other side of the course but does not know whether or not he has passed the transmitter, whereas beacons of the second type furnish a more complete signaling but with a certain ambiguity and when the pilot hears dots, for instance, he has no way of discerning in which of the sectors having the dots he finds himself.

ill! The invention relates to means for remedying w these drawbacks. It resides in providing a radio beacon transmitter which can pass from one type of signaling (two directions) to the otherone (four directions) whereby two of the four di- 39 rections of the second operating mode coincide with one of the two directions of the first mode and using this beacon during a large partof the time (for instance, for 16 seconds within a time period of seconds) for one of the operating 4 modes, preferably the signaling of the two directions and the rest of the time (in'the present case 4 seconds) for the other operating mode (signaling of four directions) by effecting simultaneously any sort of changing in the beacon transmitter (for instance the change of the low modulation frequency note) in passing from the. first to the second operating mode so that the pilot knows through this change which signal is being sent to him.

5 The functioning of the device according to the invention will be better understood in reference to the accompanying figures.

Figure 1 represents schematically in a plan view the marking of the type of two opposite directions from the beacon transmitter R;

Figure 2 shows likewise the marking of the type of four directions;

Figure 3 represents the signals obtained from the beacon transmitter according to the invention; 5

Figures 4a to 40 represent the radiation diagrams of the aerials used in one mode of embodiment of the idea of the invention; and.

Figure 5 shows schematically the arrangement of the antennas and the switches to be used.

If a radio guide system functions in accordance with the scheme of Fig. 1, the pilot when in the region A hears dots and in the region B hears dashes while the two main regions C represent the axis in which he hears a continuous note.

If a radio guide system operates, however, according to the scheme of Fig. 2, the region of dots is A1 (two sectors), that of dashes is El (two sectors), and that of the continuous note is Ci formed by four sectors of which two, for instance shall be very narrow and the other two very wide.

Fig. 3 represents the signals heard by the pilot listening to a beacon transmitter according to the invention which operates according to the type of Fig. 1 with the modulation note n1 (say 400 cycles) for 16 seconds, for instance, and, according to the type of Fig. 2, with the modulation note n2 (say 2000 cycles) during 4 seconds. The figure shows in solid and black characters the signals during 16 seconds with the frequency 121 and in blank characters bordered by lines the signals during 4 seconds with the frequency m.

It will be seen that if the airplane is on the axis C2, the pilot will observe a continuous signal whose frequency will change only during 4 seconds three times per minute, while if the airplane is outside this axis the pilot will know (provided the plane remains in this same sector at least 20 seconds) in which region among the six regions A2 A3 A4 B2 B3 B4 he finds himself, these regions being characterized respectively as follows:

A2 by hearing dots m and also dots 122 A3 by hearing dots m and a continuous note n2 A4 by hearing dots m and dashes 112 B2 by hearing dashes m and also dashes 712 B3 by hearing dashes m and a continuous note n2 B4 by hearing dashes m and dots in A practical embodiment of the idea of the invention will be given in the following, by way of example.

Referring to Figs. 4a, 4b, 4c and 5 an aerial II], If) is provided furnishing a figure of 8 dia- 55 I in a plane perpendicular to OC and fed by opposite currents. The phase of these currents will be reversed by switch MI in the rhythm of the dots and dashes thus providing the signals of the transmitter, as will subsequently appear. A second aerial H, H is" furthermore provided and constantly fed and capable of furnishing by means of simple modification either a modified figure 8 diagram having an identical instantaneous phase of radiation in all directions as shown in Fig. 4b or a figure of 8 diagram as shown in Fig. 40, having a pair of fields of opposite instantaneous polarity and a direction of zero radiation at to OC. The currents feeding doublets II, II are not switched at the dot and dash rhythm. In order to obtain these eifects, this second aerial is forined of two doublets H, I I lined up in a vertical plane parallel to OC and spaced apart slightly less than one-half Wave. It will, moreover, be sufiicient to feed these two doublets in parallel for obtaining the modified figure 8 diagram of Fig. 4b or in opposition for the figure of 8 diagram of Fig. 4c. The re sultant field is the vector sum of the field of Fig. 4a and either the field represented by Fig. 4b or 4c, depending upon the position of the reversing switch J. In one position of the switch, which may be maintained for 16 seconds, for example, the fields represented by Figs. la and' lb are combined to produce a beacon in accordance with Fig. 1, while in the other position of the switch, which may be maintained for 4 seconds, for example, the fields represented-by Figs. 4a and 4c are combined to produce a beacon in ac cordance with Fig. 2. At the same time, the phase of the current feeding the doublet system I 0, I0 is reversed with respect to the current feeding the doublet II, II at a keying rateto produce characteristic signals. The require-- ments of the system of Fig. 3 are thus satisfied.

The fields supplied by the two doublets l0, l0 and H, H are expressed respectively for each doublet, designating by d the distance between doublets and by!) the azimuths, by

tion illustrated in Fig. 40, it is necessary to subtract the expressions (1) and (2) and the difference is transformed into:

2 cos wt sin sin 0) (3) The field is therefore proportional to the term sin sin 9) and it is zero for 6:0 and 0=1r. The diagram has accordingly always two loops, the phase in one of these loops being opposite to the phase in the other loop. The shape of the loops is infiuenced by the factor but this influence is fairly small within fairly wide limits. For

or in the neighborhood of this value, it may be admitted that the loops are materially circular.

The interrupter switch Ml being maneuvered alternatively in a manner to be in one of its positions for the duration of one dot and in the inverse position for the duration of one dash, the fields supplied by system H], I 0 will have the shape shown in Fig. lain each of these positions, but the polarity will be alternately reversed. One of theloops of the diagram has been indicated with dotted line to show that its polarity is opposite to that of. the loop in full line. Likewise, the diagram of Fig. 40 represents the shape of the field of system H, II in one position of 2 sin wt cos sin 6) (4) The field is thus proportional to the term cos sin 0) it is seen that if the field is zerofor and the diagram has two loops exactly as the diagram of Fig. 40 but if d be slightly lower than 2 the term in question will be always positive and in phase in all directions.

The conditions of Fig, 1 are realized by the combination of the diagrams of the system of Figd la and of the system of Fig. 4b. The dia grams are combined in effect into a species of cardioid L, Fig. 1, the phasesbeing added for the loop in full line and being subtracted forthe loop inv dotted line. Likewise, after inversion of phase, the diagrams of Figs. 4a and 4b are combined into an inversedcardioid Ll. The intersection of the cardioids L and LI, alternated to the cadence of the dotsand dashes, supplies two routes 0 characterized by a continuous dash.

Likewise, the conditions of Figure 2 are realized by the combination of the diagrams of Fig. 4a. and of system ic. The diagrams illustrated are combined into a diagram with two loops F and Fl, Fig. 2, the phases being added. in the loops in full line of the two diagrams, and being added likewise in the loops in dotted line. .In the same manner, after inversion of phase of system l0, ID, the diagrams are combined into two loops G and GI, and the intersection of the diagrams F, FI and G, GI, alternated to the cadence of the dots and dashes, supplies four routes characterized by continuous dashes.

It should, furthermore, be noted that in order to obtain signals furnishing the maxi- 10 a variation of of the phase difference of the currents in l0, l and H, H must be assured at the moment of passing from one transmission pattern to the other. r

Fig. shows a gain, by way of example, to which the invention is not limited, an assembly of the possible arrangement of the aerials and their feeders. A switch MI provides the reversing of the phase in the rhythm of the dashes and dots in the antennas l0, iii, a reversing means :i and a contact means 0 provide, respectively, the transition from modified figure 8 to figure of 8 transmission and the adjustment of the phase (depending on whether or not a portion of the feeder equal to is short circuited) of the antennas II, II in the very slow rhythm of passing from the two-course to the four-course transmission at the rate of 16 seconds to 4 seconds, for instance.

The two distinct modulating frequencies nl and n2, referred to above, are provided by alternators P and Q which are alternately connected to a carrier frequency generator S through a switch K which is operatively connected to the reversing switch J and the short circuiting switch C. The switches may be driven by a motor K at the desired rate. The switch MI is driven at the keying rate by a keying motor N.

In reality, it is necessary to carry out this phase adjustment when passing from the transmission of Fig. 4b to that of Fig. 40 because a phase detuning 0 near 45 can well be tolerated in the position represented by Fig. 42) relative to optimum phase of the aerial H, H without notably disturbing the clearness of the signals. However, when passing from the position represented by Fig. 4b to that of Fig. 40 a phase detuning which is near 80 will be produced automatically due to the impedance change resulting from the change of connections.

What I claim is:

1. Radio-guide transmitting system comprising a first aerial having a vertical symmetry axis, means for transmitting by said first aerial a figure 8 radiation field, means for reversing the phase of said field at dot and dash rhythm, a second aerial having a common vertical symmetry axis with said first aerial, and means including switching means connected to said second aerial for transmitting by said second aerial alternatively a radiation field having identical instantaneous phase in all directions, and a figure 8 radiation field analogous to that of said first aerial but perpendicular thereto.

2. Radio-guide transmitting system comprising a first aerial having a vertical symmetry axis,

means for transmitting by said first aerial a figure of 8 radiation field, means for reversing the phase of said field at dot and dash rhythm, a second aerial having a common vertical symmetry axis with said first aerial, and means in- 5 'cluding switching means connected to said second aerial for transmitting by said second aerial alternatively a radiation field having identical instantaneous phase in all directions, and a figure of 8 type field analogous to that of said first aerial but perpendicular to the latter, the duration of said transmissions being unequal.

3. Radio-guide transmitting system comprising a first aerial having a vertical symmetry axis, means for transmitting by said first aerial a figure of 8 type radiation field, means for reversing the phase of said field at dot and dash rhythm, a second aerial having a common vertical symmetry axis with said first aerial, and means including switching means connected to said second aerial for transmitting by said second aerial alternatively a radiation field havin identical instantaneous phase in all directions, and a figure of 8 radiation field analogous to that of said first aerial but perpendicular thereto, means for feeding said aerials by a modulated high frequency current, and means for changing the modulation frequency synchronously with the switching of said fields produced by the second aerial.

4. Radio-guide transmitting system comprising a first aerial constituted of two vertical doublets disposed at a predetermined distance about a symmetry point, means for feeding said doublets in phase opposition, means for reversing the feeding phase of said doublets at dot and dash rhythm, a second aerial having a vertical symmetry axis in the said symmetry point, and means including switching means connected to said second aerial for transmitting by said second aerial alternatively a modified figure 8 radiation field having identical instantaneous phase in all directions, and a figure of 8 radiation field analogous to that of said first aerial but perpendicular thereto.

5. Radio-guide transmitting system comprising a first aerial having a vertical symmetry axis, means for transmitting by said first aerial a figure of 8 type radiation diagram, means for reversing the phase of said field at dot and dash rhythm, a second aerial constituted of two vertical doublets separated by a distance slightly less than a half wavelength of radiated energy and disposed symmetrically about said symmetry axis of the first aerial, and switching means for changing feeding connections of said doublets so as to feed them alternatively in parallel and in phase opposition, the durations of each feeding manner being unequal.

6. Radio-guide transmitting system comprising a first aerial having a vertical symmetry axis, means for transmitting by said first aerial a figure of 8 radiation field, means for reversing the phase of said diagram at dot and dash rhythm, a second aerial having a common vertical symmetry axis with said first aerial, and means including switching means connected to said second aerial for transmitting by said second aerial alternatively a modified figure 8 radiation field having identical instantaneous phase in all directions, and a figure of 8 radiation field analogous to that of said first aerial but perpendicular thereto, means for feeding said aerials by a, high frequency current, and means for changing by 90 the phase between the currents in both'aerials synchronously with said switching in the second aerial.

7. Radio-guide transmitting system comprising a first aerial having a vertical symmetry axis, means for transmitting by said first aerial a figure of 8 radiation field, means for reversing the phase of said field at dot and dash rhythm, a second aerial having a common vertical symmetry axis with said first aerial, and means including switching means connected to said second aerial for transmitting by said second aerial alternatively a modified figure 8 radiation field khaving identical instantaneous phase in all dihigh frequency current, a loop inserted in the feeding connection of said second aerial, the length of said loop being equal to a quarter wave length of the'feeding current, and a switch for alternatively short-circuiting and opening said loop synchronously with said switching in the second aerial.

YVES ROCARD. 

